Recently, mirror displays have been proposed for applications such as digital signage (e.g. Patent Literatures 1 to 4). A mirror display includes a half mirror plate provided on the front surface of a display device so that the display device can function as a mirror. The mirror display provides video images owing to display light emitted from the display device and is also usable as a mirror by reflecting external light.
Known examples of an optical member with reflecting function include vapor-deposited metal films, dielectric multilayers, multilayer reflective polarizers, nano-wire grid polarizers (e.g. Patent Literatures 5 and 6), circularly-polarized light separating sheets utilizing selective reflection of cholesteric liquid crystals (e.g. Patent Literature 7).